Yuping Xie, Jia Zhou, Sisi Chen, Yanyan Cui, Yunfei Ma, Lichun Mao, Kai Zhang, Xuhao Hu, Ye Zhang, Chunyan He, Chunying Chen, Ziwei Chen, Liangnian Wei, Ruixin Wang, Xinyi Lu, Yufang Zhang, Yun Chen, Guoyang Liao, Ying Liu, Yaling Wang, Xi Chen, Lijuan Shen, Liu Ye, Mengyu Guo, Nasha Qiu, and Jia Luo
Effective vaccines are vital to the fight against the COVID-19 global pandemic. As a critical component of a subunit vaccine, the adjuvant is responsible for strengthening the antigen-induced immune responses. Here, we present a new nanovaccine that comprising the Receptor-Binding Domain (RBD) of spike protein and the manganese nanoadjuvant (MnARK), which induces humoral and cellular responses. Notably, even at a 5-fold lower antigen dose and with fewer injections, mice immunized with the MnARK vaccine immunized mice showed stronger neutralizing abilities against the infection of the pseudovirus (~270-fold) and live coronavirus (>8-fold) in vitro than that of Alum-adsorbed RBD vaccine (Alu-RBD). Furthermore, we found that the effective co-delivery of RBD antigen and MnARK to lymph nodes (LNs) elicited an increased cellular internalization and the activation of immune cells, including DC cells, CD4+ and CD8+ T lymphocytes. Our findings highlight the importance of MnARK adjuvant in the design of novel coronavirus vaccines and provide a rationale strategy to design protective vaccines through promoting cellular internalization and the activation of immune-related pathways., Graphical abstract New nanovaccine that comprises RBD of spike protein and the manganese nanoadjuvant (MnARK) induces humoral and cellular responses.